Use ClassHierarchy.applyChanges() in MixinFullResolution.

pkg/kernel/lib/src/incremental_class_hierarchy.dart

 // Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 library kernel.incremental_class_hierarchy;
 
 import 'dart:collection';
 import 'dart:math';
 
 import 'package:kernel/ast.dart';
 import 'package:kernel/class_hierarchy.dart';
@@ skipping 61 matching lines @@
 class IncrementalClassHierarchy implements ClassHierarchy {
   /// The next unique identifier for [_ClassInfo]s.
   int _nextId = 0;
 
   /// The mapping from [Class]es to the corresponding [_ClassInfo]s.
   /// The map is ordered in such a way that classes are after superclasses.
   /// It is filled lazily as the client requests information about classes.
   final Map<Class, _ClassInfo> _info = new LinkedHashMap<Class, _ClassInfo>();
 
   @override
+  ClassHierarchy applyChanges(Iterable<Class> classes) {
+    if (classes.isEmpty) return this;
+    return new IncrementalClassHierarchy();
+  }
+
+  @override
   void forEachOverridePair(Class node,
       callback(Member declaredMember, Member interfaceMember, bool isSetter)) {
     _ClassInfo info = _getInfo(node);
     for (var supertype in node.supers) {
       var superNode = supertype.classNode;
       var superInfo = _getInfo(superNode);
 
       var superGetters = superInfo.interfaceGettersAndCalls;
       _reportOverrides(info.implementedGettersAndCalls, superGetters, callback);
       _reportOverrides(info.declaredGettersAndCalls, superGetters, callback,
@@ skipping 620 matching lines @@
 class _LubHeap extends Heap<_ClassInfo> {
   @override
   bool sortsBefore(_ClassInfo a, _ClassInfo b) => sortsBeforeStatic(a, b);
 
   static bool sortsBeforeStatic(_ClassInfo a, _ClassInfo b) {
     if (a.depth > b.depth) return true;
     if (a.depth < b.depth) return false;
     return a.id < b.id;
   }
 }